From the global zone, use the zlogin command with the -S option
to access the zone, for example, my-zone.

global# zlogin -S my-zone

How to Use zlogin to Shut Down a Zone

Note - Running init0 in the global zone to cleanly shut down a Solaris
system also runs init0 in each of the non-global zones on
the system. Note that init0 does not warn local and remote
users to log off before the system is taken down.

Use this procedure to cleanly shut down a zone. To halt a
zone without running shutdown scripts, see How to Halt a Zone.

You must be the global administrator in the global zone to perform
this procedure.